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Research And Simulation Of The Multistage Architecture And Scheduling Algorithm Based On Clos

Posted on:2011-01-21Degree:MasterType:Thesis
Country:ChinaCandidate:X W DuFull Text:PDF
GTID:2178360308464645Subject:Microelectronics and Solid State Electronics
Abstract/Summary:PDF Full Text Request
With the explosion of communication traffic in Internet, the network capacity need to constantly upgrade, single-stage switches cannot implement in scalable switches due to scheduling algorithm and IC implementation complexity. Therefore, multi-stage exchange network consisting of several switch elements is commonly used in solution case. On the other hand, the traditional scheduling algorithms used in multi-stage switch networks mostly ignore the input business features, such as: different rates of port access, delay or different service levels and so on, which can be improved in scalability and QoS (Quality of Service).First, this paper described the single-stage switch architecture, and based on which presented three-stage Clos switching network structure and the non-blocking condition. Then this paper analyses the routing issues, which leads to the conventional Clos switch fabric scheduling algorithms: random distribution (RD: Random Dispatching) and concurrent round robin dispatching algorithm (CRRD: Concurrent Round-Robin Dispatching) algorithm. By analyzing the algorithms' steps, we found that the two algorithms need to pass a lot of control information and cannot distinguish between different rates ports.In view of the traditional algorithms' shortcomings, this paper proposes a business-oriented scheduling algorithm-DBAA (Distributed Bandwidth Allocation Algorithm). DBAA implements bandwidth allocation and traffic congestion control through the speed control in the input port and the bandwidth allocation in the output port. In the input module, the algorithm need to implement features include detection of VOQ's state changes, carrying the corresponding status information by cell header and adjusting sending rate. The output module completes the total bandwidth allocation and sends the bandwidth allocation information. In order to implement DBAA algorithm, three-stage Clos structure should be modified: speed control module,queue management and time-stamp sorter should be added in the input module. A bandwidth allocation module should be added in the output module.Finally, the Clos switching network is modeled in use of system-level modeling language SystemC. Simulation results shows: DBAA can take flow attributes into account and easily achieve load balance. Compared with CRRD, DBAA achieves smaller delay under both uniform traffics and burst traffics, and achieves 100% throughput quickly. Using SystemC modeling more accurately reflect delay performance, and can support advance software development, and early follow-up micro-architecture exploration.
Keywords/Search Tags:multi-stage switch, 3-stage Clos, DBAA, Quality of Service
PDF Full Text Request
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